Agricultural biotechnology, and particularly plant biotechnology, has become recognized as one of the principal areas for the application of biotechnology techniques. Systems exist for transforming plant cells and regenerating complete plants from the transformed cells; structural gene and gene regulatory regions continue to be identified; and the need for plants with genetically engineered traits such as insect resistance and drought resistance remains strong.
A problem with the expression of foreign genes in plants is the clonal variation in the expression of the same gene in independent transformants: a problem referred to as "position effect" variation. No completely satisfactory method of obviating this problem has yet been developed, and there is accordingly a continued need for solutions to this problem.
L. Mlynarova, Approaching the Lower Limits of Transgene Variability, The Plant Cell 8, 1589-1599 (1996) is concerned with Tobacco only. Monocots are neither nor disclosed nor suggested. In addition, Mlynarova is only concerned with an F2 generation produced by selfing the F1 generation.
PCT Application WO94/07902, titled Method for Increasing Expression and Reducing Expression Variability of Foreign Genes in Plant Cells, (published 14 Apr. 1994) it is stated that "where two matrix attachment regions are employed, they may be the same or different." (page 5, lines 13-15).